imx: imx6sx-sabreauto: convert to use DM QSPI driver

To support DM QSPI driver:
 - Add -u-boot.dtsi to modify n25q256a@0 and n25q256a@1 compatible string
   to "spi-flash" and add "num-cs" property.
 - Enable DM SPI and DM SPI FLASH configurations
 - Remove iomux settings of qspi1 in board codes which is not needed
   for DM driver.

Signed-off-by: Ye Li <ye.li@nxp.com>
diff --git a/arch/arm/dts/imx6sx-sabreauto.dts b/arch/arm/dts/imx6sx-sabreauto.dts
index a4c2627..9643d1f 100644
--- a/arch/arm/dts/imx6sx-sabreauto.dts
+++ b/arch/arm/dts/imx6sx-sabreauto.dts
@@ -96,6 +96,29 @@
 	};
 };
 
+&qspi1 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_qspi1_1>;
+	status = "okay";
+	ddrsmp=<2>;
+
+	flash0: n25q256a@0 {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "micron,n25q256a";
+		spi-max-frequency = <29000000>;
+		reg = <0>;
+	};
+
+	flash1: n25q256a@1 {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "micron,n25q256a";
+		spi-max-frequency = <29000000>;
+		reg = <1>;
+	};
+};
+
 &iomuxc {
 	imx6x-sabreauto {
 		pinctrl_i2c2_1: i2c2grp-1 {
@@ -112,6 +135,23 @@
 			>;
 		};
 
+		pinctrl_qspi1_1: qspi1grp_1 {
+			fsl,pins = <
+				MX6SX_PAD_QSPI1A_DATA0__QSPI1_A_DATA_0  0x70a1
+				MX6SX_PAD_QSPI1A_DATA1__QSPI1_A_DATA_1  0x70a1
+				MX6SX_PAD_QSPI1A_DATA2__QSPI1_A_DATA_2  0x70a1
+				MX6SX_PAD_QSPI1A_DATA3__QSPI1_A_DATA_3  0x70a1
+				MX6SX_PAD_QSPI1A_SCLK__QSPI1_A_SCLK     0x70a1
+				MX6SX_PAD_QSPI1A_SS0_B__QSPI1_A_SS0_B   0x70a1
+				MX6SX_PAD_QSPI1B_DATA0__QSPI1_B_DATA_0  0x70a1
+				MX6SX_PAD_QSPI1B_DATA1__QSPI1_B_DATA_1  0x70a1
+				MX6SX_PAD_QSPI1B_DATA2__QSPI1_B_DATA_2  0x70a1
+				MX6SX_PAD_QSPI1B_DATA3__QSPI1_B_DATA_3  0x70a1
+				MX6SX_PAD_QSPI1B_SCLK__QSPI1_B_SCLK     0x70a1
+				MX6SX_PAD_QSPI1B_SS0_B__QSPI1_B_SS0_B   0x70a1
+			>;
+		};
+
 		pinctrl_uart1: uart1grp {
 			fsl,pins = <
 				MX6SX_PAD_GPIO1_IO04__UART1_TX		0x1b0b1